The present invention relates to fluid pumps and more particularly to a brushless pump for pumping a liquid in a cooling system.
Various electric motor driven fluid pump constructions are known including those generally referred to as gear rotor pumps, such as that disclosed in U.S. Pat. No. 5,035,588 and turbine vane type fluid pumps, such as that disclosed in U.S. Pat. No. 5,265,997. Typically, fluid pumps use electric motors with brushes wherein electrically conductive brushes are engaged with a commutator connected to windings to make an electrical connection therewith to generate a rotating magnetic field which spins a rotor to drive the pumping mechanism. The electromechanical connection between the brushes and the windings can provide a varied or intermittent contact therebetween which reduces the efficiency of the pump and may ultimately lead to failure of the pump, due to mechanical wear of the brushes.
A pump with a brushless electric motor such as that disclosed in U.S. Pat. No. 5,096,390, is also well known and may be used to pump a liquid in a coolant system. In this pump, an electronic controller or driver circuit controls the excitation of various stator windings to control the operation of the motor. This pump has a sealed enclosure separating the rotor from the stator windings and the electronic controller circuit to isolate the stator windings and the circuit from the liquid in the pump. Therefore, the motor stator and electronic controller circuitry are not directly cooled by the pumped fluid, and must be cooled by some conventional means such as conduction and/or air convection. This limits the power rating of the motor and electronic controller circuitry. In addition, the increased gap size between the rotor and the stator required to accommodate the seal cup reduces the efficiency of the motor. Further, the pump is not constructed to be disposed within a reservoir containing the liquid coolant and to do so requires a sealed housing enclosing the entire pump assembly which increases manufacturing and assembly costs. Mounting the pump exteriorly of the reservoir requires sealed connections between the pump and the reservoir and also increases the overall size of the cooling system.
A brushless liquid pump constructed to be received within a liquid reservoir of a cooling system to deliver coolant under pressure to a manifold assembly through which the fluid is discharged onto various electronic components to cool them. The pump has a pumping assembly, a rotor, a stator and an electronic control circuit which controls the operation of the pump and each of which is immersed in liquid coolant in the pump to cool them as the coolant flows through the pump. This reduces the operating temperature of the pump enabling a higher power rating on the motor and controller circuitry which in turn permits a reduction in overall size of the pump per unit fluid power. Further, because each component within the pump can be exposed to the liquid in the pump, no sealed enclosures are needed for the coolant pump as a whole or for any component therein and the pump can be received directly in the reservoir.
In one embodiment, the brushless pump is constructed to be disposed within a reservoir containing the liquid coolant to deliver that coolant from the reservoir to a manifold assembly wherein the coolant is sprayed onto the object to be cooled. In another embodiment, the brushless coolant pumps are constructed to be disposed within a first manifold in a manifold assembly which directs the liquid coolant to at least one additional manifold downstream thereof to apply the liquid coolant to the object to be cooled.
Objects, features and advantages of this invention include providing a brushless coolant pump which can be disposed within a liquid reservoir, provides liquid cooling of both the pump motor and the electronic circuitry which drives the motor, reduces the operating temperature of the pump, improves the reliability of the pump, permits a reduction in the overall size of the pump per unit of fluid power, can be readily adapted to a manifold assembly to provide cooling of a plurality of objects, does not require any sealed enclosures or sealed connections, is of relatively simple design and economical manufacture and assembly, is compact, durable, reliable and has a long and useful life in service.